Perforating die



PERFORATING DIE Filed June 23, 1932 2 Sheets-Sheet 1 //VI/E/VT-OR 2 Sheets-Sheet 2 IIIIIIII IIIIIIIIIIIIIII l E N TO R I W 5-.

/arro NEK 1934- c. s. KNIGHT PERFORATING DIE WWW //W Patented Jan. 2, 1934 PERFORATING DIE Chesterton S. Knight, Brockton, Mass., assignor to Geo. Knight & Co. Inc., Brock-ton, Mass, a corporation of Massachusetts Application June 23, 1932. Serial No. 618,847

10 Claims.

This invention relates to perforating dies of the type used chiefly, but not exclusively, in the shoe industry. Dies of this character are used very extensively for the purpose of ornamenting portions of a shoe upper and other parts made of leather or similar sheet materials.

It has been the usual practice heretofore to make the die plate for such a die in three pieces or sections; namely, a top plate or face plate, a

back or base plate, and an intermediate hardened steel plate. The perforating tubes are manufactured to a high degree of exactness, usually in a precision lathe, and they are pressed into holes drilled accurately both as to size and position in the top plate above mentioned. The lower ends of these tubes rest upon the intermediate hardened plate. They are all of substantially the same height, a tolerance of not more than one or two thousandths of an inch ordinarily being permitted, and consequently, the upper ends of the tubes are maintained in substantially the same horizontal plane by virtue of the fact that they are all backed up by the hardened plate. They are supported partly by the latter plate and partly also by their pressed or driven fit in the holes of the face plate. Each tube has a central bore through which the small section or pill of leather which it cuts from the work is forced, and the hardened plate has holes of approximately the same, but usually very slightly larger, diameter than the bores of the tubes to permit these pills to pass through. For the same reason the base plate is out out or recessed in line With the holes in the hardened plate so that the pills can drop freely through it.

It will be observed that a die of this construction requires a great deal of drilling, particularly if the pattern is of an intricate design, and that this drilling operation must be performed with an exceptionally high degree of accuracy. The

manufacturing operations on such a die are further complicated by the fact that the bores of the smaller perforating tubes may have a diameter as small as fifteen thousandths of an inch,

those in several of the smaller sizes ranging from this figure to sixty-five thousandths. Due to the manner in which these tubes are mounted it is necessary to use drills only slightly larger than said bores in making the holes through the intermediate plate. In addition, the holes drilled in the hardened plate must register very accurately with those in the face plate since any inaccuracy, particularly in the smaller sizes, is likely to cause the pills to jam where they pass from the perforating tubes into the holes in the intermediate TES PATENT OFFICE plate. In fact, this frequently occurs, both from the cause just mentioned and also due to other conditions, thus making it necessary to take the die apart, to remove the plugged tubes and replace them with. new ones. The present invention de als especially with the conditions above described. It aims to improve the construction of perforating dies with a view to simplifying the manufacturing operations, reducing the liability of errors in such operations,

elfecting economies in the expense of manufacfor use in such dies.

The nature of the invention will be readily understood from the following description when read in connection with the accompanying drawings, and the novel featur eswill be particularly pointed out in the appended claims.

In the drawings, Figure 1 is a plan view of a typical perforating die embodying features of this invention;

Fig. 2 is an edge view of the die shown in Fig. 1;

Fig. 3 is a vertical, sectional view approximately on the line 33, Fig. 1, but on a much larger scale than the latter figure Figs. 4 and 5 are vertical, sectional views of individual perforating tubes shown in Figs. 1 and 3, but on a much larger scale than in either of the latter figures;

Fig. 6 is a plan view of a portion of a die illustrating a modified construction embodying the invention;

Fig. '7 is a sectional view 6; and

on the line 7-7, Fig.

Fig. 8 is a fragmentary sectional view. of a construction similar to Fig. 3 but illustrating a modification.

Referring first to Figs.

1, 2 and 3, it will be observed that the die structure there shown includes a die plate 2 which preferably consists of a single integral piece has a smooth flat top and of metal. This plate one or more relatively large recesses 3 extending thereinto from the lower face of the plate.

A series of holes 4 is drilled through the portion of the plate between the upper surface and the bottom of the recesses 3, these holes being designed to receive the perforating tubes 5. of tubes used'in any die The number and arrangement necessarily will vary with the pattern or the design which the die is to make in the leather.

The particular die press the tube into the die plate.

shown in Figs. 1, 2 and 3, for the purposes of explaining the invention, is intended to cut and perforate a fancy tongue for a sport shoe. This die, therefore, includes a knife 6 of the peculiar outline shown in Fig. l to cut the body portion of the tongue to the desired shape. The knife customarily is milled out of steel, as better shown in Fig. 3, and has an integral base which is secured to the die plate 2 by screws.

Cooperating with the perforating tubes 5 and the knife 6 is a stripper plate 7 which is supported by a series of springs 8, as in prior die constructions of this general type. The strip of stock or leather S rests on this plate and is 10- cated by spring pressed. positioning pins 9 similar to those heretofore used in perforating dies.

These dies are intended particularly for use in such machines as that shown in Patent No.

. 1,448,751, these machines including a reciprocating head 10 with means for guiding a strip of relatively thick paper 12 under the head so that after the leather has been positioned and the head 10 descends, it forces the leather strip S down upon the cutting edges of the perforating tubes 5 and the knife 6, this movement continuing until all of the cutting instrumentalities have been forced through the leather and have cut very slightly into the paper strip 12. As the head rises the plate 'Tis lifted by the springs 8 and carries the leather strip S upwardly with it, thus stripping it from the cutting devices, the stripper plate having holes through which these devices project when the plate is fully depressed.

An especially important feature of this invention resides in the construction and mounting of the perforating tubes5. It will be seen from an inspection of Fig. 3 that in this die the tubes,

- instead of being mounted in a face plate and having their inner ends backed up by a hardened intermediate plate, are supported solely by shank portions of the tubes pressed or driven into the holes 4' in the die plate and by shoulders which rest on the upper surface of the die plate 2. Each tube has a cutting edge at its upper end and the distance betwen the shoulder on the tube and its cutting edge is made uniform in all of the tubes so that the cutting edges of the tubes are shoulders I; and c, the lower of these shoulders resting'on the upper surface of the die plate 2, as above described. Projecting downwardly from this body portion is a substantially cylindrical smooth surfaced shank d which has a driven or pressed fit in the hole 4 in the die plate, the lower end of: said shank being chamferedor bevelled slightly, as shown, to facilitate the driving or pressing operation. During this operation the upper shoulder 12 on the body a is useful in affording a firm bearing for the tool used to tion of the tube also includes an upright extension 1 which is of cylindrical form for the great-- er part of its length but tapers gradually near its upper end to a, cutting edge u The bore h of the tube is of a uniform'diameter for, say, ten

The body poror fifteen thousandths of an inch below the cutting edge g and then gradually widens to about the point 7' and remains of uniform diameter from the latter point to the bottom of the tube.

When the cutting edge of a tube of this construction is forced through the leather it makes a clean cut, taking a pill or plug of accurate dimensions out of the leather. The next succeeding cut forces the first pill further down the tube and into the portion of the tube which is wider and through which, therefore, the pill will move fairly freely. The clearance, however, is not sufficient to permit the pill to fall through the tube. For example, in one of the smaller tubes the bore at the cutting edge 51 may be twenty-six thousandths. At the point 7' it would widen out to thirty-three thousandths, and this dimension would be maintained throughout the rest of the tube. Typical dimensions for such a tube would be as follows:

Outside diameter of shank d and part 1', sixtyone thousandths. Outside diameter of body portion a between the shoulders, seventy-nine thousandths. Vertical distance between shoulders, one-eighth of an inch, length of shank, threesixteenths of an inch in the larger tubes and ap proximately 0' e-eighth of an inch in the smaller tubes, the minimum length of said shank of the smallest tube being twice the outside diameter of the shank. cutting edge a two hundred eighteen thousandths. The r tical dimensions will be substantially the sa for all sizes of tubes, but the horizontal diinensions obviously will vary with the tube. These tubes must be made in a precisionlathe because of the extreme accuracy required, the tolerances being very low indeed. After the manufacturing operations on them have been completed they are hardened. They are made in certa designated sizes andthey may be said to be standard. The dies, however, are always special since they must be manufactured to the patt rn or design which is to be cut in the, sheet ial operated upon.

is the shoulder b is not absolutely necessary, it useful as a support against which the tool which forces the into the die plate can abi...ted. Furthermore, it is desirable to avoid a long taper above the enlarged portion a of the body of the tube, particularly in the tubes of sm ler sizes, since there always'some tendency where a taper is'used and the tubes are placed close to each other, for the leather to wedge be tween adjacent tubes, thus tending to bend or his k the tubes. This will be evident from an in,- spection of the relationship between the three right hand tubes shown in Fig. 3. A further adof this construction is that it prevents the location of the tubes so close to each other as to weaken leather excessively when itis perforated. In other words, the dimensions of the body portions of the tubes are made such that they determine the minimum spacing which experience has shown to be practical.

In milling out the large recesses or cavities 3 v where the tubes are bunched closely togeth r, it

Distance from upper shoulder b to is desirable not to make these recesses too large but to leave ribs or webs, such as that shown at 14, Fig. 2, to provide ample strength in the tube supporting portion of the die plate. The reduction of this part of the plate to a thickness substantially equal to the length of the tube shanks is of advantage, however, in maintaining the entire series of pills or plugs of leather in the tubes until they are discharged into the large recess 3. This arrangement, combined with the shape givn to the bores of the tubes, avoids any danger of the pills becoming jammed and plugging the tubes in the manner above described. Due to the fact that the shanks of the small size tubes are somewhat shorter than those of the larger tubes, the lower ends of the former may be set back somewhat above the bottom surface of the recess 3, but even in this relationship the danger of plugging the tubes is much less than in prior constructions, due to the fact that after the pills leave the tubes they drop into a hole which has a minimum diameter equal to that of the outside diameter of the tube shanks and consequently, considerably larger than the bores of the tubes. It frequently occurs, however, that as a leather pill is discharged from a tube it will turn over in the hole in the die plate approximately as shown in Fig. 4. The pills are held under considerable compression while in the tubes, and they therefore tend to expand upon being discharged. In order to avoid any possibility of such a pill catching in one of the holes 4 in the die plate, it is preferable to make the distance between the lower ends of the tubes and the bottoms of the recesses less than twice the outside diameter of the tube shank, this relationship applying more especially to the very small tubes. Usually the diameter of the shanks of these very small tubes is less than the thickness of the leather which is being worked upon, and consequently, the pills are longer than the diameter of the tubes. This appears to be an important reason for the tipping of the pills in the holes after they have been discharged from the lower ends of the tubes. If,

however, the proportions above described are maintained, then no more than two pills at the most can become lodged at a time in the holes below the ends of the tubes, and anyresistance which they offer is not sufficientto produce a jam that will not clear itself.

In making a die plate of the character above described, the holes are drilled for the tubes 5, the recess or recesses are milled or otherwise cut in the back of theplate, the plate is hardened, the tubes are then inserted, and the other assembling operations are performed, as will be obvious to those skilled in this art. It will be evident,

however, that the invention effects importanteconomies in the manufacture of dies of this character, particularly because of simplifying the construction of the die plates and greatly reducing the drilling operations. Since the die plate is an integral structure, there is no danger of misalining drilled holes with each'other as in the prior constructions above described. Furthermore, the number of very small drills which must be used is reduced and the size of the drills required for even the smallest size of tubes heretofore used is increased so that the delay and expense occasioned by breaking drills is lessened. For example, in manufacturing prior dies used in the shoe trade, drills as small as thirty-five thousandths of an inch in diameter were'required for certain of the perforating tubes. In dies made according to the present invention, however, the smallest drill required for the mounting of struction is far more important than the increase.

in expense for the tubes themselves. To state the matter somewhat differently, a large percentage of the work requiring great precision is transferred from the manufacture of the die plates to the manufacture of the tubes where it can be done by automatic machinery. It is taken out of the part of the die which is always special and transferred to those units which are standard.

The invention also facilitates the operation of While the perforating tubes.

repairing the dies since it is simply necessary to punch out a broken tube and replace it with a new one when such an operation is required, whereas in the old constructions such repairs re-- quired the disassembling of the die plate before atube could be'replaced. The present arrangement further avoids the necessity for positioning pins and screws heretofore required to hold thesections of the die plate together. This die construction, therefore, is superior both from the standpoint of the manufacturer and the user.

This-construction also lends itself readily to those modifications of a perforating die which sometimes are required to adapt it-to changes in design without necessitating the rebuilding of the die. For example, let it be assumed that the user of the die wishes to add more tubes at the upper end of the bunch of perforating tubes shown in Fig. 1 for the purpose of extending the perforations farther up the tongue, changing the contour of the perforated area, or for any other reason. Such a change can easily be made in the construction shown by mountingthe desired number of tubes in a removable auxiliary die plate 16, Figs. 6 and 7, and releasably securing this plate to the main die plate 2, as by screws 17-17. These tubes 5' carried by the plate 16 are made exactly like the tubes 5, but instead of being pressed into holes drilled accurately for them in the main die plate, the cylindrical portions a of the tubes 5' have a pressed or driven fit in the plate 16, while the shanks d of said tubes fit freely in holes drilled through the reduced portion of the die plateinto the cavity 3, the cavity in this case being extended so as to underlie the entire area in which the tubes are positioned. The holes so drilled through the reduced part of the die plate are not as large as the cylindrical portionsa of the tubes so that the shoulders c of the tubes 5 rest on the upper flat surface of the die plate, just as do the shoulders of the other tubes 5. Consequently, these additional or auxiliary tubes 5 are levelled in the same manner as the original group 5 of tubes. At the same time the shanks of these tubes 5' serve to position them and the auxiliary die plate 16 on the maindie plate.

The screws 17 are held in place by strong coiled springs 18 which encircle said screws, the latter being drilled and tapped to receive additional screws l9- l9 which back up the springs l8- 18. Also, the heads of the screws 1'7l-7 are cut off, or made flat at one side, as clearly shown in Fig.

sides. are parallelv with and. adj acent to the. edges. of the plate '16, the plate can be. lifted out, of; position and removed from the die. In, such; a

construction the stripper plate? usually would I have a hole 20., Fig; 6, cut through it of. sufficient i size to. permit thev passagejtherethrough of: the plate 16.

The die can thus be changed readily in thev manner just described to. permit the introduction of additional perforatingv tubes, when, desired, and

such. changes involve only very. slight modifications of'the original die structure.

' While I have herein shown and described a,typical embodiment of my invention, it will be under'stood that this disclosure has. been made rather byway of explanation than limitation, and that the invention, may be embodied in other forms without departing from thespirit or scope thereof. For example, many of theadvantages of this construction can. be obtained by dividing the I main die plate 2 along the. horizontal planesub;

stantially throughthe plane of the bottom of the recess 3 so that all. of the. drilling for theperforating tubes .will be performed in the upper sec- .tion of the die plate, the recess 3. lying entirely in the lower section. This construction is, illustrated in Fig. 8, the two. sections of-themain die plate being. indicated at 2; and. 2", respectively;

Such a modification, however, israrely of advantage. Also, whilethe die has beenshown and described'with the tubes in any upright position, sincet'nisis the-position in which the die. customarily is used, the reference to the top. and bot-1 tom surfaces of the die plate and the upper. and lowerv ends of the tubes in both thespecification and in the claims has been made for the. purposes of convenience and clearness and doesnot limit.

the parts to use in. these. positions.

"Having thus described my invention, what I desire. to'claim as new is:

1. A perforating die comprising. a die. plate having asubstantially flat top and cheer more recesses extending thereinto from the lower-.face thereof thus providing a portion of reduced thicknes's'between said top and the bottoms of said recesses, said dieplate also having a seriesof holes extending through. said reducedportion, a series.

of perforating tubes each. having a shoulderresting on. the. top of said: die .plateand each pro-- vided with a reduced, shank extending. into one of said holes and having a pressed fit therewith, the. lowerend surfaces 'ofsaid tubes. being out of contact with thermetalof saidplate, and said die plate formingthesole supportingmeans, for said tubes.

2; A perforatinsdie ompr s n a d e w t hering. a substantially flat top and one or 1110128 re cesses extending thereinto from the-lower face thereof thus providing a portion of reduced.t l -ick-v ness between said top and the bottoms of .saidr.e

' cesses, said die plate also having a seriesof holes upper end, said bore being of smaller diamete'r at and'immediately adjacent to said cutting edge.

than atotherparts ofthe tube.

3. A perforating die according. to. precedingv claim. 2. in which thedistance. between the-lower.

ne ates;

nd of, ce t n; fsaii be and he ttom of a d-r ces esis. e s han w c ou d am plate. ac of ai u e a o: having a ho d resting upon the upper surface of said plate and being provided; with a cutting edge at its upper end, thelower end surfaces of said tubes being 1 t of c nta t w th. h m a oisai l t d the istan e fro t ou de :t -th c t edges, of said tubes being substantially uniform,

5. A perforating die comprising a die plate havns..a. at. pp sur ac a r e p r at n tubes-each; having an approximately cylindrical shank driven rigidl-yinto a hole in said plate,

ea ch of said tubes also having a shoulder resting 7 upon the uppersurface of-said plate, said shank having a len th belowsaidshoulderat least twice asgreat asthe. outsidediameter of the shank, the lower end; surfaces of said tubes being out of contact with the metal of said; plate, and each tube being. provided with, a cutting edge at its-upper end.

6-. A'cutting tube. for perforating dies comprisi a body ro ided wit as o l e a n a xt nsi n r iect n wa bov said shoulder and terminating at-its upper end in a ut e de and an a pro mate y dr cal shank extending downwardly from. said ou der, said u shav ea cen ra bo ex e ding therethrough, from-its upperto its lower end of smaller diameter at and immediately adjacent tesaid cutting edge'than at otherparts oi the; tube.

'7. Acutting tube for perforating dies -compris-. ing a body provided with a shoulder, an approximately yl nd c sha ex d war y from saidshouldeusaid bedy having a portion above said shoulder which is tapered to a cutting edge, said. tubehaving a central bore which widens for a, short distance, as it extends downn ric l or on r v de wit ab upt er atits upper; and; lower ends, a smooth approxi;

from said cutting edge and thereafter is m t l y n r ca sh nke te dins dow wa ly from the, lower. of said; shoulders, said body hav n a a oximate y indrical: extension p ojec ing. upw rdl r m. he: up o sa shoulders-with a taperedend portion abovethe latt vty in .al ortion term nat n a utting. e and a ssni el. b r t n in through he i bee d i a ls diam te a a mme atelyadjacent-to said cutting Ed e than at other parts of the tube.

9 A perforating: die comprising.- a main die plate, aseries of,- perforating tubes, each having a shank, pressedtightlyinto a hole insaid plate, each of; said tubes also having a shoulder rest ing-uponthe upper surfaceof said; plate and each being, provided at -its; upper end with a cutting edge, anauxiliary die plate removably secured on theupper surface of saidmain die plate, one or.more.perforating .tubes secured in said auxiliarydieplate, each of thelattertubeshaving por securing said auxiliary die plate to said main die plate.

10. A perforating die comprising a main die plate having a substantially flat top and one or more recesses extending thereinto from the lower face thereof thus providing a portion of reduced thickness between said top and the bottoms of said recesses, said die plate also having a series of holes extending through said reduced portion, a series of perforating tubes each having a shoulder resting on the top of said die plate and each provided with a reduced shank extending into one of said holes and having a pressed fit therewith, said die plate forming the sole supporting means for said tubes, an auxiliary die plate positioned on said main die plate, one or more perforating tubes secured rigidly in said auxiliary die plate, each of the latter tubes hav- 

